Process of forming loose materials into coherent bodies



Patented 'Aprt 28, 1925.

"UNITED STATES 1,535,032 PATENT tomes.

ALBERT'L. STILLMAN, OF PLAINFIELD,,NEW JERSEY, ASSIGNOR TO THE SMBLTERS GENERAL BRIQUETTE CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF- NEW YORK.

PROCESS OF FORMING LOOSE MATERIALS INTO COHERENT BODIES.

No Drawing.

To all whom it may concern:

Be it known that I, ALBERT L. STILLMAN, a citizen of the United States of America, and a resident of Plainfield, county of Union, State of New Jersey, have invented certain new and useful Improvements in Processes of Forming Loose Materials into Coherent Bodies, of which the following is a specification. I

My present invention relates to briquetting and like processes for the forming of loose material into coherent bodies. The method is a plicable for various purposes among whic 1 I will :name particularly the making of briquettes from blast furnace flue dust and from phosphate rock (apatite).

When blast furnace flue dust is to be briquetted according to my method, this material should be fresh so that it will contain a percentage of FeO sufiicient to secure the characteristic chemical reaction herein after more fully set forth. This percentage is about ten per cent although a content of FeO as low as 7% is 'sufficient. If blast furnace flue dust is allowed to stand for any length of time it will gradually become oxidized and will then not contain enough FeO to make it suitable for treatment according to my present process. My invention enables such blast furnace flue dust to be inexpensively formed into coherent bodies and particularly into small blocks or briquettes for charging it back into the blast furnace. Ordinarily bla t furnace flue dust,

if charged back into the blast furnace, will prove detrimental to the operation. since it will clog and impede the blast and finally riding the blastit will emer e again at the .top of the blast furnace Without being re duced by the operation.

According to my invention, when applied to blast furnace flue dust, I cause the formation of iron sesqui-oxide in the flue dust, which sesqui-oxide acts as a hinder or cement. The production of such sesqui-oxide is accomplished by mixing with the flue (lust a corrosive acid agent which reacts with the Fe(), or with such part thereof as is necesear to accomplish the result, to produce the sai sesqui-oxide Fe O The reaction is stimulated by means of pressure, said pressure also serving to agglomerate the mass into blocks or briquettes.

In detail I may proceed as follows: The

Application filed October 8, 1922. Serial No. 692,165.

same method briquette other loose materials containing ten per cent or more of ferrous oxide, for instance, iron ores of that composition.

If the corrosive agent consists of green vitriol I prefer to use a solution of ten parts of crystals in ninety parts of water and to add this solution to the flue dust or other material containing FeO in the proportion of ten parts of solution to ninety parts of loose material. A reaction begins at once between the ferrous oxide and the iron sulphate and thls action may be stimulated if desired by rolling the mixture after it leaves the pug-mill or other mixing apparatus, in a grinding apparatus, especially a Chilean mill or edge-runner, which rolling action improves the final product but is not essential to my process. The mixture having been rolled or not is then passed into a rotary press having rolls with accurately faced pockets which serve to shape the mixture into lrlocks or briquettes. In these pockets the mixture is subjected to a sequence of pressures equal to a steady pressure of from three thousand to six thousand pounds per square inch. The reaction which has been going on all the time is much stimulated by this pressure and when the briquettes drop from this press they are hot and steaming, but the reaction is by no means complete and continues after the briquettes have left the press. The action of the press also serves to permeate the mixture thoroughly with the cementing medium, that is to say, with the Fe O formed by the reaction.

This reaction which, as stated above, begins'as soon as the iron sulphate solution is mixed with the loose material, and continues during and after the briquetting operation, may be explained asfollowss-In the resence of water the ferrous oxide and the iron sulphate react with each other to form sulphuric acid andferrous hydrate as may be expressed by the following equation:

(1 FeO-i-FeSO +311 0:

) H SO +2Fe(0H), The ferrous hydrate reacts with water to form ferric hydrate as may be expressed by the equation l (3) 2Fe(OH) +hea t:Fe O +3H O The water vapor escapes chiefly after the briquettes have left the press, and the iron sesqui-oxide forms a .cement or binder to hold the loose material together so that ooferrous oxide to herent bodies or bri uettes will be formed. The sulphuric acid formed by the reaction as expressed in e uation l reacts with the orm ferrous hydrate and iron sulphate which may be expressed by the equation:

It will be noted that the reaction is cyclical and; results in the formation of iron sulphate. Of course the several reactions represented by the above equations take place practically at the same time. They would continue indefinitely were it not for the fact that the water is radually driven off by the heat evolved. ith the passing of the water the acid radical takes up sufficient iron present to satisfy it, that is to say at the end of the reaction the iron sulphate is present in the same quantity and condition as at the beginning.

The cementing action of the iron sesquioxide is exerted even during the mixing operation but is quite feeble unless pressure be exerted immediately thereafter, that is to say while the reaction is still going on between the loose material and the corrosive agent.

When the briquettes leave the press they are relatively weak and should, therefore, be preferably cushioned as they are delivered from the press. The reaction still continues for some time after the briquettes have been discharged from the press and the hardening or setting of the briquettes will take Iace upon simply exposing them to the air.

owever, for economical reasons it is desirable to hasten this hardening process and this I can accomplish by exposing the briquettes to a very gentle air current for a period of fort -five minutes or over. The simplest way 0 efiecting this is to spread the briquettes as they come from the press for which they are required (about five ounces will be satisfactory in most cases).

Various modifications may be made without departing from the nature of my invention as set forth in the appended claims, for example, the percentage of FeO content of the flue dust as hereinbefore set forth may be varied considerably, but it is essential that an ap reciable amount of such FeO be present, at east an amount sufiicient to form a large enough quantity of F6 0, as a binder to insure the coherence of the loose material when it is pressed into briquettes.

I claim:

1. The herein described method which consists in mixin with loose material containing an appreciable amount of iron oxide (FeO), a corrosive acid medium that'will produce Fe O as a binder b reacting with said material, andforming t e mixture into coherent bodies by rolling pressure while such reaction is oing on.

2. The herein escribed method which consists in mixing with blast furnace flue dust containing an appreciable amount of F e0, a corrosive acid medium that will produce a binder by converting FeO into Fe O and forming the mixture into coherent bodies by pressure while such conversion is going on.

3. The herein described method which consists in mixing with loose material to be formed by pressure into coherent bodies, said material containing an ap reciable amount of FeO a corrosive acid me ium that will produce a binder by reactlng with said material, forming the mixture into coherent bodies by pressure while such reaction is going on,

and then exposing such bodies to a gentle current of air.

4. The method of forming briquettes which consists in addin to loose, material containing an apprecialie amount of iron oxide (F e0), a medium which will produce a binder by an exothermic reaction with said oxide to form iron sesqui-oxide F6 0, subjecting the mixture to pressure while such reaction is going on to form such mixture into briquettes and employing the heat generated by the reaction to dry the briquettes so formed.

In testimony whereof, I have hereunto set my hand.

ALBERT L. STILLMAN. 

